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Abstract

Changes in histamine, putrescine, and cadaverine concentrations in fresh and
stored bluefish (Pomatomus saltatrix) were determined using a new HPLC method. The
HPLC method utilized a 5.0% (w/v) trichloroacetic acid (TCA) extraction, pre-column
fluorescamine derivitization, and fluorescence detection. The derivatives were stable
over 24 h. The 5% TCA extraction produced percent recoveries of 98.6%, 98.7, and
100.0% for histamine, cadaverine, and putrescine respectively. The HPLC process
including extraction, derivatization, and HPLC analyses was conducted in less than 45
minutes.
Fresh bluefish was found to contain between <1 ppm and 99 ppm histamine, and
no cadaverine or putrescine. Fresh bluefish fillets were stored at 5, 10, and 15 degrees C until
sensory rejection. Fresh bluefish fillets inoculated with Morganella morganii were also
stored at the same conditions. Histamine levels as high as 2200 ppm were observed in
the inoculated fish stored at 15 degrees C. Overall, histamine achieved higher levels in the
bluefish pieces inoculated with Morganella morganii. Histamine was present in greater
amounts than putrescine and cadaverine in the bluefish samples. Histamine levels at each
temperature exceeded the 50 ppm advisory level established by the FDA before 100%
sensory rejection. Putrescine levels increased at each temperature during storage.
Cadaverine was present only in uninoculated bluefish stored at 15 degrees C. Consumer risk
from histamine poisoning seems to be the greatest in those fish stored at 5 degrees C where
acceptance levels were higher and histamine levels above 100 ppm were observed.
The presence of histamine-forming bacteria in fish-processing facilities was
studied. Environmental sampling techniques were conducted in the Hampton Roads area
of Virginia in fish-processing facilities that regularly handle scombroid fish or other fish
which are known to accumulate histamine levels greater than 50 ppm. Surfaces that
come into contact with the fish were swabbed and the histamine-forming bacteria from
these areas were identified. One isolate each of Klebsiella ozaenae and Vibrio
alginolyticus, and two isolates of Aeromonas sp. were found in the processing facilities.
The study concluded that histamine-forming bacteria do not make up a large part of the
microflora associated with fish-processing facilities. Fishing vessels were also sampled
and no histamine-forming bacteria were identified.